Policy control method and device

ABSTRACT

Embodiments of the present invention relate to a policy control method and device. The method includes: receiving, by a PCRF, NAT entry information sent by a NAT device; obtaining, by the PCRF, a first PCC rule according to the NAT entry information, where the first PCC rule is a PCC rule including an IP address to be translated by the NAT device; and sending, by the PCRF, the first PCC rule to a gateway device, so that the gateway device executes the first PCC rule. According to the embodiments of the present invention, it can be ensured that the gateway device correctly executes the PCC rule.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2011/074675, filed on May 25, 2011, which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present invention relate to the field ofcommunications technologies, and in particular, to a policy controlmethod and device.

BACKGROUND

With the popularity of Internet technologies, the number of terminaldevices increases rapidly, and each terminal device needs to obtain avalid Internet protocol (Internet Protocol, IP for short) address (suchas, IPv4 address) when communicating with the Internet; therefore, validIP addresses become scarce resources. To solve insufficiency of valid IPaddresses, a built-in or an external network address translation(Network Address Translation, NAT for short) device on a gateway devicemay be used to establish NAT entry information, so as to translate agroup of IP address information into another group of IP addressinformation, for example, translate a group of private IP addresses(such as, IPv6 address) and private network port numbers of a local areanetwork into valid IP addresses (such as, IPv4 address) and publicnetwork port numbers of the Internet.

A policy and charging control (Policy and Charging Control, PCC forshort) architecture defined by the 3rd generation partnership project(3rd Generation Partnership Project, 3GPP for short) may be mainlyformed by an application function entity (Application Function, AF forshort), a policy and charging rules function entity (Policy and ChargingRules Function, PCRF for short), and a policy and charging enforcementfunction entity (Policy and Charging Enforcement Function, PCEF forshort). The PCRF receives application-layer session information that isdynamically provided by the AF, generates corresponding PCC rulesaccording to the session information, and delivers the PCC rules to thegateway device, so that the gateway device executes these PCC rules.

However, after the NAT device is introduced, the AF can only identify anIP address (such as, IPv4 address) obtained through translating by theNAT device, while the gateway device can only identify an IP address(such as, IPv6 address) to be translated by the NAT device; therefore,after the PCRF generates, according to the session information of theAF, a PCC rule including the IP address obtained through translating bythe NAT device and delivers the PCC rule to the gateway device, thegateway device cannot identify the IP address in the PCC rule, therebycausing that the gateway device cannot execute the PCC rule.

SUMMARY

Embodiments of the present invention provide a policy control method anddevice, which are used to ensure that a gateway device correctlyexecutes a PCC rule.

An embodiment of the present invention provides a policy control method,including:

receiving, by a PCRF, NAT entry information sent by a NAT device;

obtaining, by the PCRF, a first PCC rule according to the NAT entryinformation, where the first PCC rule is a PCC rule including an IPaddress to be translated by the NAT device; and

sending, by the PCRF, the first PCC rule to a gateway device, so thatthe gateway device executes the first PCC rule.

An embodiment of the present invention provides another policy controlmethod, including:

receiving, by a gateway device, NAT entry information sent by a NATdevice;

receiving, by the gateway device, a first PCC rule sent by a PCRF, wherethe first PCC rule is a PCC rule including an IP address obtainedthrough translating by the NAT device;

translating, by the gateway device, the first PCC rule into a second PCCrule according to the NAT entry information, where the second PCC ruleis a PCC rule including an IP address to be translated by the NATdevice; and

executing, by the gateway device, the second PCC rule.

An embodiment of the present invention further provides a PCRF,including:

a receiving unit, configured to receive NAT entry information sent by aNAT device;

an obtaining unit, configured to obtain a first PCC rule according tothe NAT entry information, where the first PCC rule is a PCC ruleincluding an IP address to be translated by the NAT device; and

a sending unit, configured to send the first PCC rule to a gatewaydevice, so that the gateway device executes the first PCC rule.

An embodiment of the present invention further provides a gatewaydevice, including:

a first receiving unit, configured to receive NAT entry information sentby a NAT device;

a second receiving unit, configured to receive a first PCC rule sent bya PCRF, where the first PCC rule is a PCC rule including an IP addressobtained through translating by the NAT device;

a translating unit, configured to translate the first PCC rule into asecond PCC rule according to the NAT entry information, where the secondPCC rule is a PCC rule including an IP address to be translated by theNAT device; and

an executing unit, configured to execute the second PCC rule.

It can be seen from the foregoing technical solutions that, in theembodiments of the present invention, the PCC rule including the IPaddress obtained through translating by the NAT device can betranslated, according to the NAT entry information, into the PCC ruleincluding the IP address to be translated by the NAT device, or the PCCrule including the IP address to be translated by the NAT device can beobtained according to the NAT entry information, thereby ensuring thatthe gateway device correctly executes the PCC rule.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention or in the prior art more clearly, the following brieflyintroduces accompanying drawings required for describing the embodimentsor the prior art. Apparently, the accompanying drawings in the followingdescription show merely some embodiments of the present invention, andpersons of ordinary skill in the art may further obtain other drawingsaccording to these accompanying drawings without creative efforts.

FIG. 1 a is a schematic flow chart of a policy control method accordingto an embodiment of the present invention;

FIG. 1 b is a schematic flow chart of a policy control method accordingto another embodiment of the present invention;

FIG. 2 is a schematic flow chart of a policy control method according toanother embodiment of the present invention;

FIG. 3 is a schematic flow chart of another policy control methodaccording to another embodiment of the present invention;

FIG. 4 is a schematic flow chart of another policy control methodaccording to another embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a PCRF according to anotherembodiment of the present invention;

FIG. 6 is a schematic structural diagram of a gateway device accordingto another embodiment of the present invention; and

FIG. 7 is a schematic diagram of a PCC architecture to which theembodiments corresponding to FIG. 1 a, FIG. 1 b, and FIG. 2 areapplicable.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, theembodiments to be described are merely a part rather than all of theembodiments of the present invention. All other embodiments obtained bypersons of ordinary skill in the art based on the embodiments of thepresent invention without creative efforts shall fall within theprotection scope of the present invention.

FIG. 1 a is a schematic flow chart of a policy control method accordingto an embodiment of the present invention. As shown in FIG. 1 a, thepolicy control method in this embodiment may include the followingsteps:

101 a: A PCRF receives NAT entry information sent by a NAT device.

The NAT entry information may include information related to an addressto be translated by the NAT device, and information related to anaddress obtained through translating by the NAT device, for example, theNAT entry information may include a source IP address (a source IPaddress before translation and a source IP address after translation), aprotocol type, and a source port number (a private network source portnumber before translation and a public network source port number aftertranslation).

Optionally, the PCRF may specifically receive NAT entry information thatis directly sent by the NAT device to the PCRF.

Optionally, the PCRF may also specifically receive NAT entry informationthat is sent by the NAT device through a gateway device to the PCRF.

Optionally, the PCRF may also specifically receive NAT entry informationthat is sent by the NAT device through an AF to the PCRF.

102 a: The PCRF obtains a first PCC rule according to the NAT entryinformation, where the first PCC rule is a PCC rule including an IPaddress to be translated by the NAT device.

Optionally, the PCRF may specifically translate a generated second PCCrule into a first PCC rule according to the NAT entry information, wherethe second PCC rule is a PCC rule including an IP address obtainedthrough translating by the NAT device.

Optionally, the PCRF may also specifically obtain, according to the NATentry information, an IP address to be translated by the NAT device, andgenerate a first PCC rule according to the IP address to be translatedby the NAT device.

103 a: The PCRF sends the first PCC rule to a gateway device, so thatthe gateway device executes the first PCC rule.

In this embodiment, the NAT device may be built in the gateway device,or may also be disposed external to the gateway device, which is notlimited in the embodiment of the present invention.

In this embodiment, the PCRF receives the NAT entry information sent bythe NAT device, and obtains, according to the NAT entry information, thePCC rule including the IP address to be translated by the NAT device, sothat the PCRF can send the obtained PCC rule to the gateway device,thereby ensuring that the gateway device can correctly execute the PCCrule.

The policy control method in this embodiment may be applied to variouscommunication systems, such as, a code division multiple access (CodeDivision Multiple Access, CDMA for short) system, a wideband codedivision multiple access (Wideband Code Division Multiple Access, WCDMAfor short) system, a general packet radio service (General Packet RadioService, GPRS for short) system, and a long term evolution (Long TermEvolution, LTE for short) system.

The gateway device may be a gateway GPRS supporting node (Gateway GPRSSupporting Node, GGSN for short) in the CDMA system, the WCDMA system,and the GPRS system, and may also be a network element in the LTEsystem, such as a packet data network gateway (Packet Data NetworkGateway, PGW for short) and an evolved packet data gateway (EvolvedPacket Data Gateway, ePDG for short).

FIG. 1 b is a schematic flow chart of a policy control method accordingto another embodiment of the present invention. As shown in FIG. 1 b, aPCRF may specifically translate a generated second PCC rule into a firstPCC rule according to NAT entry information, where the first PCC rule isa PCC rule including an IP address to be translated by a NAT device, andthe second PCC rule is a PCC rule including an IP address obtainedthrough translating by the NAT device. Specifically, the following maybe included:

101 b: A PCRF receives NAT entry information sent by a NAT device.

The NAT entry information may include information related to an addressto be translated by the NAT device, and information related to anaddress obtained through translating by the NAT device, for example, theNAT entry information may include a source IP address (a source IPaddress before translation and a source IP address after translation), aprotocol type, and a source port number (a private network source portnumber before translation and a public network source port number aftertranslation).

102 b: The PCRF translates a generated second PCC rule into a first PCCrule according to the NAT entry information, where the second PCC ruleis a PCC rule including an IP address obtained through translating bythe NAT device, and the first PCC rule is a PCC rule including an IPaddress to be translated by the NAT device.

103 b: The PCRF sends the first PCC rule to a gateway device, so thatthe gateway device executes the first PCC rule.

In this embodiment, the PCRF receives the NAT entry information of theNAT device that is sent by the NAT device, and translates, according tothe NAT entry information, the generated second PCC rule including theIP address obtained through translating by the NAT device into the firstPCC rule including the IP address to be translated by the NAT device, sothat the PCRF can send the first PCC rule obtained through translatingto the gateway device, thereby ensuring that the gateway device cancorrectly execute the PCC rule.

In order to make the methods provided by the embodiments of the presentinvention more comprehensible, the following takes an LTE system as anexample. FIG. 2 is a schematic flow chart of a policy control methodaccording to another embodiment of the present invention. In thisembodiment, a PGW allocates an IPv6 address to a user equipment (UserEquipment, UE for short), and the UE needs to initiate a service to anAF having an address of an IPv4 format. As shown in FIG. 2, the policycontrol method in this embodiment may include the following steps:

201: A UE sends an uplink service packet to a NAT device through a PGW,where the uplink service packet includes a source IP address (an IPv6address of the UE), a destination IP address (a specific IPv6 addressincluding an IPv4 address of an AF), a protocol type, a source portnumber (a private network port number corresponding to the UE), and adestination port number (a port number corresponding to the AF).

Before 201, the UE may request domain name resolution of the AF from adomain name system (Domain Name System, DNS for short), and the DNSreturns a specific IPv6 address to the UE, where the specific IPv6address includes the IPv4 address of the AF.

202: The NAT device performs address-related translation, translates theIPv6 address of the UE into an IPv4 address, translates the privatenetwork port number corresponding to the UE into a public network portnumber, and establishes NAT entry information, where the NAT entryinformation includes a source IP address (the IPv6 address of the UEbefore translation and the IPv4 address after translation), the protocoltype, and a source port number (the private network port numbercorresponding to the UE before translation and the public network portnumber after translation).

203: The NAT sends the uplink service packet obtained throughtranslating to the AF, where the uplink service packet obtained throughtranslating includes a source IP address (the IPv4 address of the UE),the destination IP address (the IPv4 address of the AF), the protocoltype, a source port number (the public network port number correspondingto the UE), and the destination port number (the port numbercorresponding to the AF).

204: The NAT sends the established NAT entry information to a PCRF.

Optionally, the NAT may also send the established NAT entry informationto a PCRF through the PGW or the AF.

It should be noted that, 203 and 204 are not performed in a fixedsequence.

205: The AF sends an IP address (the IPv4 address obtained throughtranslating by the NAT device) of the UE and service information of theUE to the PCRF.

206: The PCRF generates a corresponding PCC rule according to the IPaddress (the IPv4 address obtained through translating by the NATdevice) of the UE, the service information of the UE, and subscriptionprofile of the UE that is obtained from a subscription profilerepository (Subscription Profile Repository, SPR for short), where thePCC rule includes the IP address (the IPv4 address obtained throughtranslating by the NAT device) of the UE.

207: The PCRF translates the IP address of the UE in the PCC ruleaccording to the obtained NAT entry information, that is, translates theIPv4 address into a corresponding IPv6 address.

208: The PCRF sends the PCC rule obtained through translating to thePGW.

209: The PGW executes the obtained PCC rule obtained throughtranslating.

Specifically, the AF sends a downlink service packet (that is, aresponse packet of the uplink service packet) to the UE through the NATdevice and the PGW. The downlink service packet sent by the AF includesa source IP address (the IPv4 address of the AF), a destination IPaddress (the IPv4 address of the UE), the protocol type, a source portnumber (the port number corresponding to the AF), and a destination portnumber (the public network port number corresponding to the UE). Aftermatching performed by the NAT device according to the established NATentry information, the downlink service packet received by the PGWincludes a source IP address (the specific IPv6 address including theIPv4 address of the AF), a destination IP address (the IPv6 address ofthe UE), the protocol type, the source port number (the port numbercorresponding to the AF), and a destination port number (the privatenetwork port number corresponding to the UE). Then, the PGW maps,according to the obtained PCC rule obtained through translating, and theIP address (the IPv6 address obtained through translating by the NATdevice) of the UE that is included in the PCC rule, the receiveddownlink service packet to a bearer corresponding to the PCC rule fortransmission.

In this embodiment, the PCRF receives the NAT entry information that issent by the NAT device directly or indirectly (through the PGW or theAF), and translates, according to the NAT entry information, a generatedPCC rule including an IP address obtained through translating by the NATdevice into a PCC rule including an IP address to be translated by theNAT device, so that the PCRF can send the PCC rule obtained throughtranslating to the gateway device, thereby ensuring that the gatewaydevice can correctly execute the PCC rule.

FIG. 7 is a schematic diagram of a PCC architecture to which theembodiments corresponding to FIG. 1 a, FIG. 1 b, and FIG. 2 areapplicable. An interface between a NAT device and a PCRF is newly added.NAT entry information is transmitted to the PCRF device through thenewly added interface between the NAT device and the PCRF, so that thePCRF may complete translation of a PCC rule, or translation of an IPaddress, and deliver an identifiable rule to a gateway.

FIG. 3 is a schematic flow chart of another policy control methodaccording to another embodiment of the present invention. As shown inFIG. 3, the policy control method in this embodiment may include thefollowing steps:

301: A gateway device receives NAT entry information sent by a NATdevice.

The NAT entry information may include information related to an addressto be translated by the NAT device, and information related to anaddress obtained through translating by the NAT device, for example, theNAT entry information may include a source IP address (a source IPaddress before translation and a source IP address after translation), aprotocol type, and a source port number (a private network source portnumber before translation and a public network source port number aftertranslation).

302: The gateway device receives a first PCC rule sent by a PCRF, wherethe first PCC rule is a PCC rule including an IP address obtainedthrough translating by the NAT device.

The first PCC rule is generated by the PCRF.

303: The gateway device translates the first PCC rule into a second PCCrule according to the NAT entry information, where the second PCC ruleis a PCC rule including an IP address to be translated by the NATdevice.

304: The gateway device executes the second PCC rule.

In this embodiment, the NAT device may be built in the gateway device,or may also be disposed external to the gateway device, which is notlimited in the embodiment of the present invention.

In this embodiment, the gateway device receives the NAT entryinformation sent by the NAT device, and translates, according to the NATentry information, the received first PCC rule including the IP addressobtained through translating by the NAT device into the second PCC ruleincluding the IP address to be translated by the NAT device, therebyensuring that the gateway device can correctly execute the PCC rule.

The policy control method in this embodiment may be applied to variouscommunication systems, such as, a code division multiple access (CodeDivision Multiple Access, CDMA for short) system, a wideband codedivision multiple access (Wideband Code Division Multiple Access, WCDMAfor short) system, a general packet radio service (General Packet RadioService, GPRS for short) system, and a long term evolution (Long TermEvolution, LTE for short) system.

The gateway device may be a gateway GPRS supporting node (Gateway GPRSSupporting Node, GGSN for short) in the CDMA system, the WCDMA system,and the GPRS system, and may also be a network element in the LTEsystem, such as a packet data network gateway (Packet Data NetworkGateway, PGW for short) and an evolved packet data gateway (EvolvedPacket Data Gateway, ePDG for short).

In order to make the methods provided by the embodiments of the presentinvention more comprehensible, the following takes an LTE system as anexample. FIG. 4 is a schematic flow chart of another policy controlmethod according to another embodiment of the present invention. In thisembodiment, a PGW allocates an IPv6 address to a user equipment (UserEquipment, UE for short), and the UE needs to initiate a service to anAF having an address of an IPv4 format. As shown in FIG. 4, the policycontrol method in this embodiment may include the following steps:

401: A UE sends an uplink service packet to a NAT device through a PGW,where the uplink service packet includes a source IP address (an IPv6address of the UE), a destination IP address (a specific IPv6 addressincluding an IPv4 address of an AF), a protocol type, a source portnumber (a private network port number corresponding to the UE), and adestination port number (a port number corresponding to the AF).

Before 401, the UE may request domain name resolution of the AF from adomain name system (Domain Name System, DNS for short), and the DNSreturns a specific IPv6 address to the UE, where the specific IPv6address includes the IPv4 address of the AF.

402: The NAT device performs address-related translation, translates theIPv6 address of the UE into an IPv4 address, translates the privatenetwork port number corresponding to the UE into a public network portnumber, and establishes NAT entry information, where the NAT entryinformation includes a source IP address (the IPv6 address of the UEbefore translation and the IPv4 address after translation), the protocoltype, and a source port number (the private network port numbercorresponding to the UE before translation and the public network portnumber after translation).

403: The NAT sends the uplink service packet obtained throughtranslating to the AF, where the uplink service packet obtained throughtranslating includes a source IP address (the IPv4 address of the UE),the destination IP address (the IPv4 address of the AF), the protocoltype, a source port number (the public network port number correspondingto the UE), and the destination port number (the port numbercorresponding to the AF).

404: The NAT sends the established NAT entry information to the PGW.

It should be noted that, 403 and 404 are not performed in a fixedsequence.

405: The AF sends an IP address (the IPv4 address obtained throughtranslating by the NAT device) of the UE and service information of theUE to a PCRF.

406: The PCRF generates a corresponding PCC rule according to the IPaddress (the IPv4 address obtained through translating by the NATdevice) of the UE, the service information of the UE, and subscriptionprofile of the UE that is obtained from a subscription profilerepository (Subscription Profile Repository, SPR for short), where thePCC rule includes the IP address (the IPv4 address obtained throughtranslating by the NAT device) of the UE.

407: The PCRF sends the generated PCC rule to the PGW.

408: The PGW translates the IP address of the UE in the PCC ruleaccording to the obtained NAT entry information, that is, translates theIPv4 address into a corresponding IPv6 address.

409: The PGW executes the PCC rule obtained through translating.

Specifically, the AF sends a downlink service packet (that is, aresponse packet of the uplink service packet) to the UE through the NATdevice and the PGW. The downlink service packet sent by the AF includesa source IP address (the IPv4 address of the AF), a destination IPaddress (the IPv4 address of the UE), the protocol type, a source portnumber (the port number corresponding to the AF), and a destination portnumber (the public network port number corresponding to the UE). Aftermatching performed by the NAT device according to the established NATentry information, the downlink service packet received by the PGWincludes a source IP address (the specific IPv6 address including theIPv4 address of the AF), a destination IP address (the IPv6 address ofthe UE), the protocol type, the source port number (the port numbercorresponding to the AF), and a destination port number (the privatenetwork port number corresponding to the UE). Then, the PGW maps,according to the PCC rule obtained through translating, and the IPaddress (the IPv6 address obtained through translating by the NATdevice) of the UE that is included in the PCC rule, the receiveddownlink service packet to a bearer corresponding to the PCC rule fortransmission.

In this embodiment, the PGW receives the NAT entry information that isdirectly sent by the NAT device, and translates, according to the NATentry information, a received PCC rule including an IP address obtainedthrough translating by the NAT device into a PCC rule including an IPaddress to be translated by the NAT device, thereby ensuring that thePGW can correctly execute the PCC rule.

It should be noted that, to simplify the description, the foregoingmethod embodiments are described as a series of action combinations. Butpersons skilled in the art should know that the present invention is notlimited to any described sequence of actions, because some steps mayadopt other sequences or may be performed simultaneously according tothe present invention. Moreover, persons skilled in the art should knowthat the embodiments described in the specification all belong toexemplary embodiments, and the involved actions and modules are notnecessary for the present invention.

In the foregoing embodiments, the description of each embodiment has itsemphasis, and for a part not described in detail in a certainembodiment, reference may be made to related description in otherembodiments.

FIG. 5 is a schematic structural diagram of a PCRF according to anotherembodiment of the present application. As shown in FIG. 5, the PCRF inthis embodiment may include a receiving unit 51, an obtaining unit 52,and a sending unit 53. The receiving unit 51 is configured to receiveNAT entry information sent by a NAT device; the obtaining unit 52 isconfigured to obtain a first PCC rule according to the NAT entryinformation, where the first PCC rule is a PCC rule including an IPaddress to be translated by the NAT device; and the sending unit 53 isconfigured to send the first PCC rule to a gateway device, so that thegateway device executes the first PCC rule.

Functions of the PCRFs in the embodiments corresponding to FIG. 1 andFIG. 2 may be implemented by the PCRF provided by this embodiment.

Optionally, the receiving unit 51 in this embodiment may specificallyreceive NAT entry information that is directly sent by the NAT device tothe PCRF.

Optionally, the receiving unit 51 in this embodiment may alsospecifically receive NAT entry information that is sent by the NATdevice through the gateway device to the PCRF.

Optionally, the receiving unit 51 in this embodiment may alsospecifically receive NAT entry information that is sent by the NATdevice through an AF to the PCRF.

Optionally, the obtaining unit 52 in this embodiment may specificallytranslate a second PCC rule into the first PCC rule according to the NATentry information, where the second PCC rule is a PCC rule including anIP address obtained through translating by the NAT device.

Optionally, the obtaining unit 52 in this embodiment may alsospecifically obtain, according to the NAT entry information, an IPaddress to be translated by the NAT device, and generate the first PCCrule according to the IP address to be translated by the NAT device.

In this embodiment, the PCRF receives, through the receiving unit, theNAT entry information sent by the NAT device, and then the obtainingunit obtains, according to the NAT entry information, the first PCC ruleincluding the IP address to be translated by the NAT device, so that thesending unit can send the obtained first PCC rule to the gateway device,thereby ensuring that the gateway device can correctly execute the PCCrule.

FIG. 6 is a schematic structural diagram of a gateway device accordingto another embodiment of the present invention. As shown in FIG. 6, thegateway device in this embodiment may include a first receiving unit 61,a second receiving unit 62, a translating unit 63, and an executing unit64. The first receiving unit 61 is configured to receive NAT entryinformation sent by a NAT device; the second receiving unit 62 isconfigured to receive a first PCC rule sent by a PCRF, where the firstPCC rule is a PCC rule including an IP address obtained throughtranslating by the NAT device; the translating unit 63 is configured totranslate the first PCC rule into a second PCC rule according to the NATentry information, where the second PCC rule is a PCC rule including anIP address to be translated by the NAT device; and the executing unit 64is configured to execute the second PCC rule.

Functions of the gateway device in the embodiment corresponding to FIG.3 and the PGW in the embodiment corresponding to FIG. 4 may beimplemented by the gateway device provided by this embodiment.

In this embodiment, the NAT device may be built in the gateway device,or may also be disposed external to the gateway device, which is notlimited in the embodiment of the present invention.

In this embodiment, the gateway device receives, through the firstreceiving unit, the NAT entry information sent by the NAT device, andthen the translating unit translates, according to the NAT entryinformation, the first PCC rule which includes the IP address obtainedthrough translating by the NAT device and is received by the secondreceiving unit into the second PCC rule including the IP address to betranslated by the NAT device, thereby ensuring that the executing unitcan correctly execute the PCC rule.

Persons of ordinary skill in the art may understand that, all or a partof the steps of the foregoing method embodiments may be implemented by aprogram instructing relevant hardware. The foregoing program may bestored in a computer readable storage medium. When the program runs, thesteps of the foregoing method embodiments are performed. The foregoingstorage medium includes any medium capable of storing program codes,such as a ROM, a RAM, a magnetic disk, or an optical disk.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the present inventionrather than limiting the present invention. Although the presentinvention is described in detail with reference to the foregoingembodiments, persons of ordinary skill in the art should understand thatthey may still make modifications to the technical solutions describedin the foregoing embodiments, or equivalent replacements to part oftechnical features of the technical solutions described in the foregoingembodiments; however, these modifications or replacements do not makethe essence of the corresponding technical solutions depart from thespirit and scope of the technical solutions of the embodiments of thepresent invention.

1. A policy control method, comprising: receiving, by a policy and charging rules function (PCRF) entity, network address translation (NAT) entry information sent by a NAT device; obtaining, by the PCRF, a first policy and charging control (PCC) rule according to the NAT entry information, wherein the first PCC rule is a PCC rule comprising an IP address to be translated by the NAT device; and sending, by the PCRF, the first PCC rule to a gateway device, so that the gateway device executes the first PCC rule.
 2. The method according to claim 1, wherein the obtaining, by the PCRF, a first PCC rule according to the NAT entry information comprises: translating, by the PCRF, a second PCC rule into the first PCC rule according to the NAT entry information, wherein the second PCC rule is a PCC rule comprising an IP address obtained through translating by the NAT device.
 3. The method according to claim 1, wherein the receiving, by a PCRF, NAT entry information sent by a NAT device comprises: receiving, by the PCRF, the NAT entry information that is directly sent by the NAT device to the PCRF.
 4. The method according to claim 1, wherein the NAT entry information comprises a source IP address before translation, a source IP address after translation, a protocol type, a private network source port number before translation, and a public network source port number after translation.
 5. A policy control method, comprising: receiving, by a gateway device, network address translation (NAT) entry information sent by a NAT device; receiving, by the gateway device, a first policy and charging control (PCC) rule sent by a policy and charging rules function (PCRF) entity, wherein the first PCC rule is a PCC rule comprising an IP address obtained through translating by the NAT device; translating, by the gateway device, the first PCC rule into a second PCC rule according to the NAT entry information, wherein the second PCC rule is a PCC rule comprising an IP address to be translated by the NAT device; and executing, by the gateway device, the second PCC rule.
 6. The method according to claim 5, wherein the NAT entry information comprises a source IP address before translation, a source IP address after translation, a protocol type, a private network source port number before translation, and a public network source port number after translation.
 7. A policy and charging rules function (PCRF) entity, comprising: a receiving unit, configured to receive network address translation (NAT) entry information sent by a NAT device; an obtaining unit, configured to obtain a first policy and charging control (PCC) rule according to the NAT entry information, wherein the first PCC rule is a PCC rule comprising an IP address to be translated by the NAT device; and a sending unit, configured to send the first PCC rule to a gateway device, so that the gateway device executes the first PCC rule.
 8. The PCRF according to claim 7, wherein the obtaining unit is configured to: translate a second PCC rule into the first PCC rule according to the NAT entry information, wherein the second PCC rule is a PCC rule comprising an IP address obtained through translating by the NAT device.
 9. The PCRF according to claim 7, wherein the receiving unit is configured to: receive the NAT entry information that is directly sent by the NAT device to the PCRF.
 10. A gateway device, comprising: a first receiving unit, configured to receive network address translation (NAT) entry information sent by a NAT device; a second receiving unit, configured to receive a first policy and charging control (PCC) rule sent by a policy and charging rules function (PCRF) entity, wherein the first PCC rule is a PCC rule comprising an IP address obtained through translating by the NAT device; a translating unit, configured to translate the first PCC rule into a second PCC rule according to the NAT entry information, wherein the second PCC rule is a PCC rule comprising an IP address to be translated by the NAT device; and an executing unit, configured to execute the second PCC rule.
 11. The method according to claim 1, wherein the obtaining, by the PCRF, a first PCC rule according to the NAT entry information comprises obtaining, by the PCRF, according to the NAT entry information, the IP address to be translated by the NAT device, and generating the first PCC rule according to the IP address to be translated by the NAT device.
 12. The method according to claim 1, wherein the receiving, by a PCRF, NAT entry information sent by a NAT device comprises receiving, by the PCRF, the NAT entry information that is sent by the NAT device through the gateway device to the PCRF.
 13. The method according to claim 1, wherein the receiving, by a PCRF, NAT entry information sent by a NAT device comprises receiving, by the PCRF, the NAT entry information that is sent by the NAT device through an application function (AF) entity to the PCRF.
 14. The PCRF according to claim 7, wherein the obtaining unit is configured to obtain, according to the NAT entry information, the IP address to be translated by the NAT device, and generate the first PCC rule according to the IP address to be translated by the NAT device.
 15. The PCRF according to claim 7, wherein the receiving unit is configured to receive the NAT entry information that is sent by the NAT device through the gateway device to the PCRF.
 16. The PCRF according to claim 7, wherein the receiving unit is configured to receive the NAT entry information that is sent by the NAT device through an AF to the PCRF. 